using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

public class Program

{

        static string alphaCaps = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

        static string alphaLow = "abcdefghijklmnopqrstuvwxyz";

        static string numerics = "1234567890";

        static string special = "@#$-=/";

        string allChars = alphaCaps + alphaLow + numerics + special;

        Random r = new Random();

    public string GenerateRandomStrongPassword(int length)

        {

            String generatedPassword = "";

            if (length < 4)

                throw new Exception("Number of characters should be greater than 4.");

            int lowerpass, upperpass, numpass, specialchar;

            string posarray = "0123456789";

            if (length < posarray.Length)

            posarray = posarray.Substring(0, length);

            lowerpass = getRandomPosition(ref posarray);

            upperpass = getRandomPosition(ref posarray);

            numpass = getRandomPosition(ref posarray);

            specialchar = getRandomPosition(ref posarray);

​

​

            for (int i = 0; i < length; i++)

            {

                if (i == lowerpass)

                    generatedPassword += getRandomChar(alphaCaps);

                else if (i == upperpass)

                    generatedPassword += getRandomChar(alphaLow);

                else if (i == numpass)

                    generatedPassword += getRandomChar(numerics);

                else if (i == specialchar)

                    generatedPassword += getRandomChar(special);

                else

                    generatedPassword += getRandomChar(allChars);

            }

            return generatedPassword;

        }

​

        private string getRandomChar(string fullString)

        {

            return fullString.ToCharArray()[(int)Math.Floor(r.NextDouble() * fullString.Length)].ToString();

        }

​

        private int getRandomPosition(ref string posArray)

        {

            int pos;

            string randomChar = posArray.ToCharArray()[(int)Math.Floor(r.NextDouble()* posArray.Length)].ToString();

            pos = int.Parse(randomChar);

            posArray = posArray.Replace(randomChar, "");

            return pos;

        }

    public static void Main()

    {

        Console.WriteLine("Hello World");

        Program p = new Program();

            string rs = p.GenerateRandomStrongPassword(8);

            Console.WriteLine(rs);

    }

}